Switching in the cellular communication system
Invention field
The present invention relates to the switching in the cellular communication system, and especially, but be not the switching that relates to uniquely by fast cell selection technology.
Background of invention
At present, the most ubiquitous cellular communication system is the known second generation communication system as global system for mobile communications (GSM).Can show at Michel Mouly and Marie Bernadette Pautet about further describing of GSM tdma communication system, Bay ForeignLanguage Books, 1992, " gsm system that is used for mobile communication " among the ISBN2950719007 finds.
In order further to strengthen the service and the performance of gsm communication system, many for many years enhancements and interpolation have been introduced in gsm communication system.
Such enhancement is General Packet Radio System (GPRS), and it is in order to realize the system based on the communication of grouped data in gsm communication system.Therefore, gprs system and GSM (voice) system compatible, and the many Additional Services that comprise block data communication are provided, its increase has also replenished the circuit-switched communications of legacy communications system.Further, packet-based data communication can also be supported packet-based voice service.Gprs system has been standardized as additional to existing gsm communication system, and can be introduced in the existing gsm communication system by introducing new networking component.Especially, introduce a plurality of Serving GPRS Support Nodes (SGSN) and Gateway GPRS Support Node (GGSN), so that packet-based fixed network communication to be provided.
Third generation system is spreading out the communication service that offers the mobile subscriber with further enhancing at present in a large number.Such system is the Universal Mobile Telecommunications System (UMTS) that is developing at present.About CDMA, particularly can be at " WCDMA that is used for UMTS " about the further describing of wideband CDMA (WCDMA) pattern of UMTS, Harri Holma (editor), Antti Toskala (editor), Wiley﹠amp; Sons, 2001, find among the ISBN0471486876.The core net of UMTS is to use SGSN and GGSN to set up, thereby the versatility with GPRS is provided.
For service and the function that provides by cellular communication system further is provided, beginning standardization effort to the improvement of third generation cellular communication system with on strengthening.Especially, the known job as EUTRA (the UMTS terrestrial wireless of enhancing inserts) is determined at present, is used to study the cellular technology of promoting the new future that is used for UMTS terrestrial wireless air interface.
Third generation cellular communication system trends towards using the technology that is known as soft handover, in soft handover, and the link when between transfer period, keeping between subscriber equipment and a plurality of base station.Yet,, select (FCS) to be better than soft handover for down link direction fast cell for EUTRA.It is the technology of subscriber equipment continuous monitoring from the signal quality of serving BS and the reception of one or more adjacent base station that fast cell is selected.This signal is used to estimate which base station is only serving BS at present.This system has used fast signalling mechanism, and it allows subscriber equipment to switch fast between the base station.Like this, in fast cell is selected, thereby the quick direct-cut operation between the subscriber equipment control different base station allows communication to be supported by only base station.
In EUTRA, it is a candidate likely that is used for the down link access technology that OFDM inserts (OFDMA).Opposite with cdma system, for OFDMA execution soft handover may be from the non-overlapped time and the Frequency Distribution of a plurality of base stations during soft handover.Yet this is being uneconomic aspect rare Radio Resource, so fast cell selects to promise to be more suitably solution.Further, for EUTRA, will use the fast dispatch of subscriber equipment in the base station, this base station is because complicated and not-so-practical harmony that need be between the performed scheduling of different base station, so it is unsuitable for soft handover.
Yet fast cell selects also to have correlative questions and shortcoming.For example, the signaling mistake may take place, thereby cause selected base station not receive sub-district gravity treatment message, thereby cause dropped calls or go offline.
Further, when between different districts, changing, be difficult in and do not use complicated algorithm with communicating by letter of doubling and under relevant base station stored data conditions, keep the continuity of data.Yet, the bandwidth of the communication link that this need increase in fixed network, the function of increase and memory capacity.Therefore, when in inter-cell transitions, may frequently interrupt and/or take place great delay.
For example, for the system that uses retransmission mechanism, need to wait for that being forwarded to previous serving BS (comes from for example core net; Base station controller; Or another base station) all data are all successfully confirmed by subscriber equipment, or need be transmitted the data of duplicating to new base station.Therefore, retransmitting in the cell change of finishing (increasing the stand-by period) or the cell change of (the causing the waste of transfer resource) of aborted all may be undecided.Therefore, cause the bandwidth lose of additional delay or increase.Further, in order effectively to be switched, equally need the data buffer of a plurality of base stations synchronously, that is, the base station of new choosing need know which data successfully is sent to subscriber equipment.This has introduced extra complexity.
Therefore, a kind of improved system will have more superiority, and especially, the delay of a kind of flexibility that allows to increase, reduction, the bandwidth consumption of reduction, be convenient to the complexity operating, reduce and/or the system of improved performance of handoffs will have more superiority.
Summary of the invention
Therefore, the present invention seeks to preferably individually or alleviate, reduce or eliminate one or more in the above-mentioned shortcoming of mentioning with compound mode ground.
According to a first aspect of the invention, provide cellular communication system, having comprised: at least the first base station and second base station; At least the first subscriber equipment; Be used to control the equipment of first subscriber equipment direct-cut operation between first base station and second base station, this equipment comprises: the device of service quality (QoS) feature that is used for determining the communication of first subscriber equipment, and the device that is used to transmit the data of this communication, this communication is set in response to this feature and to first base station and second base station or only transmits data to one of first base station and second base station.
The present invention is implemented in the improvement performance in the cellular communication system, and realizes improved performance of handoffs especially.Can optimize performance and operation for the specific needs and the preference of the independent service that offers first subscriber equipment.For example, the delay of service may reduce, and this is disadvantageous especially when the simple valid function of other services of permission.May obtain more effective Radio Resource uses.In many cases, the present invention is implemented in the traffic that reduces between the networking component of fixed network of cellular communication system.
Different with soft handover, for direct-cut operation, transmission in the time of not from the identical data of different base station.System can use fast cell to select especially and direct-cut operation can be that fast cell is selected to switch.
The device that is used to transmit data can be set to be used for to first value of QoS feature and transmit data and to second value of QoS feature and only transmit data one of in first base station and second base station to first base station and second base station.
For example, the device that is used for transmitting data can be positioned at first base station, and data can be sent to first base station from for example radio network controller and be sent to second base station from first base station then like this.
The optional feature according to the present invention, have standard compliant delay restriction then transmit data if retransmission unit is set to the communication of QoS character representation to first base station and second base station, and if the communication of QoS character representation do not have standard compliant delay restriction then only transmit data to one of first base station and second base station.
This has realized the improvement performance in the cellular communication system.Especially, it has been realized having low bandwidth needs and has reduced the simple operations that postpones delay-sensitive services.
The optional feature according to the present invention, support service in real time then transmit data if retransmission unit is set to the indication communication of QoS feature to first base station and second base station, and if QoS feature indication communication support the non real-time service then only transmit data to one of first base station and second base station.
This has realized the improvement performance in the cellular communication system.Especially, real-time service has been realized having low bandwidth needs and lowered the simple operations that postpones.
The optional feature according to the present invention, if data are forwarded to first base station and second base station, then first and second base stations are set to operate with the shared data transmission pattern during switching interval, and the shared data transmission pattern comprises that packet is by the two is sent to first subscriber equipment from first and second base stations.
This can improve performance of handoffs, and especially, can provide the delay of reduction and/or operation easily.Packets different in the shared data transmission pattern are sent from first and second base stations.
The optional feature according to the present invention, cellular communication system further comprise and are used to the communication between first and second base stations during the switching interval and divide the classification apparatus of whole resource allocations.
The operation that this can facilitate is also supported the shared data transmission pattern, and does not need the resource outside the communication service allocation.For example this resource allocation can be that time-frequency resources distributes, such as the distribution to the carrier frequency of given interval.
The optional feature according to the present invention, classification apparatus are set to revise during switching interval and divide.
Especially, this division can be modified, and compares higher when the beginning of switching interval when switching interval finishes so that be dispensed to being divided in of second base station.For example, the division of resource can be that resource is shifted to second base station from first base station gradually.This feature can realize improved performance of handoffs.
The optional feature according to the present invention, first and second base stations are set to send data with orthogonal resource allocation to first subscriber equipment during switching interval.
This can be so that operate and/or provide improved performance.
The optional feature according to the present invention, orthogonal resource allocation are quadratures in time domain.
This can be so that operate and/or provide improved performance.
The optional feature orthogonal resource allocation is a quadrature in frequency domain according to the present invention.
This can be so that operate and/or provide improved performance.
The optional feature according to the present invention, communication be by the retransmission mechanism support, and wherein first base station is set to support re-transmission to the packet that had before been sent by first base station during switching interval.
This can be so that operate and/or provide improved performance.Especially, it can provide effective retransmission performance, reduces the data volume that need be forwarded or be copied to second base station simultaneously.
Especially, first base station can retransmit the needed packet of any re-transmission, but the initial transmission of new data packet is to carry out from second base station.
The optional feature according to the present invention, communication are by the retransmission mechanism support, and wherein second base station is set to send the previous packet that is not sent by first base station during switching interval.
This can be so that operate and/or provide improved performance.
The optional feature according to the present invention, second base station is set to receive the indication that comes from first subscriber equipment, and this indication has indicated from which packet of communication to be begun to send.
This can be so that operate and/or provide improved performance.
The optional feature according to the present invention is receiving this indication from the re-transmission feedback message of first subscriber equipment to the first base station.
This can be so that operation.This second base station is by monitoring from the resend messages (for example, ACK/NACK message) of first subscriber equipment to the first base station to determine from which suitable data grouping to begin to send.
The optional feature according to the present invention, second base station are set to receive the transmission indication, and this transmission dial gauge is shown in switching interval when finishing not by successfully from a plurality of packets of first base station transmission.
For example can receive this indication from another networking component of subscriber equipment, first base station or fixed network.This can provide effectively and the operation and the performance of low-complexity.
The optional feature according to the present invention, first subscriber equipment comprises the monitoring arrangement that is used for supervisory work feature during switching interval; With the error detection occurs device that is used to detect mistake, this error responses is inconsistency between operating characteristics that is monitored and shared data transmission pattern.
This has realized improved performance and improved error performance is provided especially.This feature has realized switching the earlier detection of mistake, and has therefore realized more reliable performance of handoffs.Especially, monitoring arrangement can monitor that whether first and/or second base station is according to the operational requirements of shared data transmission pattern and parameter and operate, if not words can determine error detection occurs.
Optional feature according to the present invention, if only to first base station and one of them forwarding shared data of second base station, then data forwarding device is set to transmit data up to switch transition time (handover switch time) to first base station, and is set to transmit data to second base station in switch transition after the time.
This is convenient to operation and/or improved performance is provided.
Optional feature according to the present invention, first base station is set to be supported in switch transition after the time, to the retransmission mechanism of the packet that sends before.
This is convenient to operation and/or improved performance is provided.The switch transition time that is used to transmit data can be different change-over time with air interface, this air interface in change-over time aerial interface communication be transformed into second base station from first base station.For example, retransmitted data packet can be continued in first base station in the spacer segment of switch transition after the time.Therefore, in this spacer segment, new data packet is forwarded to second base station rather than first base station, simultaneously in order to finish uncompleted re-transmission, still comes from first base station to the air interface communication of subscriber equipment.
The optional feature according to the present invention, data forwarding device are set in response to determine the switch transition time from the cell change signaling of first subscriber equipment.
This is convenient to operation and/or improved performance is provided.For example can determine the switch transition time, perhaps determine the switch transition time in response to being included in the clear and definite time indication in the message from time of reception to the cell change message that comes from subscriber equipment.
Optional feature according to the present invention, first base station comprises the equipment that is used to control direct-cut operation.
The device that is used to transmit is set to transmit the data of first inside of base station or can forward it to second base station.This can provide improved performance and suitable realization in many examples.
According to a further aspect in the invention, the equipment that is used to control the direct-cut operation of first subscriber equipment between first base station and second base station is provided, this equipment comprises: be used for determining first subscriber equipment communication service quality (QoS) feature device and be used in response to this QoS feature and to first base station and second base station the two or only transmit the device of communication data to one of first base station and second base station.
According to a further aspect in the invention, provide and controlled first subscriber equipment in first base station of cellular communication system and the method for the direct-cut operation between second base station, this method comprises: determine service quality (QoS) feature of the communication of first subscriber equipment, and in response to this QoS feature to first base station and second base station the two or only one of them transmits data to first base station and second base station.
These and other aspect of the present invention, feature and advantage will be by becoming apparent with reference to the embodiment that describes below.
The accompanying drawing summary
With reference to the accompanying drawings, embodiments of the invention are only described in the mode of example, wherein,
Fig. 1 is the schematic diagram according to the cellular communication system of the embodiment of the invention;
Fig. 2 shows the example of equipment that is used to control direct-cut operation according to the embodiment of the invention; And
Fig. 3 shows the example according to the direct-cut operation of the embodiment of the invention.
Inventive embodiments describes in detail
Following description is conceived to the embodiment of the invention, and they are applicable to the current goal of the EUTRA cellular communication system that uses retransmission mechanism.Yet apparent, the present invention is not restricted to this application, but can be applied to many other cellular communication systems.
Fig. 1 shows the example of cellular communication system 100, and embodiments of the invention can be used in this system.
In cellular communication system, the geographic area is divided into a plurality of sub-districts, and each sub-district is by base station services.The base station is connected to each other by the fixed network that can send data between the base station.Provide service via wireless communication link to subscriber equipment (for example third generation subscriber equipment (UE), remote terminal, travelling carriage or the like) by the base station in the sub-district, subscriber equipment place.
When subscriber equipment moved, it may move to the overlay area of another base station from the overlay area of a base station, promptly from a sub-district to another sub-district.When subscriber equipment when move the base station, it enters the overlapping covered of two base stations, and serve as reasons new base station of user equipment to change is supported in this overlapping region.Along with subscriber equipment moves further into new sub-district, it continues to be supported by new base station.The transfer or the switching of Here it is known inter-cell user equipment.
Typical cellular communication system typically covers whole country, and comprises the hundreds of sub-district of supporting thousands of even subscriber equipmenies up to a million.Communication from the subscriber equipment to the base station is called as up link, and the communication from the base station to the subscriber equipment is called as down link.
In the example of Fig. 1, first subscriber equipment 101 is in first sub-district of being supported by first base station 103.
First base station 103 is coupled to a RNC107, and a RNC107 further is coupled to second base station 105, and the neighbor cell of the sub-district of first base station 103 is supported in this second base station.RNC carries out the controlled function of many relevant air interfaces, comprises RRM and to suitable base station and from suitable base station data is carried out route.
The one RNC107 is coupled to core net 109.Core net is connected to each other RNC and can operates the data that are used between any two RNC of route, thus make in the sub-district subscriber equipment can with the communications of user equipment in any other sub-district.In addition, core net comprises gateway function, is used to be connected to external network, PSTN (PSTN) for example, thus allow subscriber equipment to communicate by the communication terminal that land line is connected with land line phone and other.Further, core net comprises the needed many functions of management legacy cellular communications networks, comprises route data, authorization control, and resource allocation, the user charges, user equipment authority identification or the like.
Core net 109 further is coupled to the 2nd RNC111, and the 2nd RNC111 is coupled to the 3rd base station 113.The 3rd subscriber equipment 115 is supported in the 3rd base station 113.
Selectively, the RNC function can be embedded in the base station self.
In the object lesson of Fig. 1, first subscriber equipment 101 is called out relevant with EUTRA well afoot and the 3rd subscriber equipment 115.At first, first subscriber equipment 101 is supported by first base station 103.First subscriber equipment, 101 execution fast cell selection algorithms and persistent surveillance are from the signaling of first base station 103 and 105 receptions of second base station.In example, first subscriber equipment 101 moves to the sub-district of second base station 105 from the sub-district of first base station 103.At certain point, first subscriber equipment, 101 employed fast cell choice criteria are determined should carry out from the direct-cut operation of 103 to second base stations 105, first base station.
Cognoscible is that fast cell selection technology may cause specific ping-pong, wherein first subscriber equipment 101 can be in first and second base stations 103, carry out back and forth between 105 and switch, fully move in the sub-district of second base station 105 up to first subscriber equipment 101.To those skilled in the art, can use hysteresis (hysteresis) to deal with this ping-pong.
When first subscriber equipment 101 has determined that need be from the direct-cut operation of 103 to second base stations 105, first base station time, it sends cell switch message to first and second base stations 103,105.In response, first base station 103 and second base station 105 enter switching operation modes, and communication is changed from first base station 103 to second base station 105 gradually in this pattern.
In system, the downlink traffic that will be transferred into first subscriber equipment 101 receives and is assigned to therefrom first base station 103 and/or second base station 105 by a RNC107.The one RNC107 typically will receive forecast information (advanceinformation) from first subscriber equipment 101, and the switching of generation from 103 to second base stations 105, first base station expresses possibility.System according to Fig. 1, the one RNC107 comprises the function that enters switch mode, to be assigned to only be first and second base stations 103 to the down link data of first subscriber equipment 101 in switch mode, one of them of 105 or first and second base stations 103,105 both, depend on service quality (QoS) feature of downlink traffic.
Selectively, if the RNC function is embedded in the BTS, then for example, depend on service quality (QoS) feature of downlink traffic, first base station 103 may distribute data to the second base station 105.
Fig. 2 shows the example that is used to control the equipment 200 of direct-cut operation according to the embodiment of the invention.This equipment can be carried out in a RNC107, and will be described with reference to this (selectively, it can for example be carried out among the BTS103 at for example BTS).
The one RNC107 comprises the base-station interface 201 that links to each other by the suitable communication link and first and second base stations 103,105, and wherein this suitable communication link is well-known to those skilled in the art.Therefore, base-station interface 201 can to/transmit and receive data from first base station 103 and second base station 105.
The one RNC107 further comprises and is set to the core network interface 203 that is connected with core net 109.Specifically, core network interface 203 can be to the networking component of core net and from the networking component of core net, and for example (Serving GPRS Support Node) transmits and receive data.
Base-station interface 201 and core network interface 203 are coupled to switch controller 205, and switch controller 205 is set to control the switching by the subscriber equipment of RNC107 service.Specifically, thus switch controller 205 is set to control downlink traffic will be routed to and transmit to given subscriber equipment for which base station.
The one RNC107 further comprises the QoS controller 207 of service quality (QoS) feature that is set to 101 communications of definite first subscriber equipment.
The QoS feature can be any suitable QoS feature, for example can allow the indication, conversation cutting off rate or the error rate that interrupt.Yet in described embodiment, the QoS feature is the indication to the dynamic need of communication.Especially, the QoS feature can be the indication to the admissible delay of data transmitted in packets.
This indication can be for example the service of being supported to be the indication of serving in real time or non real-time is served.Service in real time can be for example streaming media service or packetized voice data conversation (for example, ip voice), even wherein less delay or little interruption all are clearly.On the contrary, the non real-time service typically can be tolerated long interruption or delay.For example, in addition relatively large delay can not make Intranet browse service to be affected significantly.
The cognoscible QoS of being controller 207 can use any suitable algorithm or mode to determine the QoS feature.Typically, in cellular communication system, communication service is set up with a plurality of specific qos parameters, and system must guarantee to satisfy this qos parameter.For example, a plurality of QoS features may be determined in advance, and when setting up new communication services, select specific QoS classification to be used for this service.In such embodiments, QoS controller 207 can be by determining that service belongs to or definite simply QoS feature corresponding to which QoS classification.
In described system, switch controller 205 is coupled to QoS controller 207, provides the indication that the given communication service that will switch is belonged to which QoS classification to this QoS controller.Therefore, in specific examples, when first subscriber equipment 101 provides when showing that it enters fast cell and select to switch the indication in contingent zone, QoS controller 207 provides indication to the delay restriction of the communication service of first subscriber equipment 101 to switch controller 205.Specifically, its can to indicate communication service be in real time service or non real-time service.
In response, switch controller 205 continues to enter in two different switch modes of operation one.
(for example, the non real-time service in) first operator scheme, be forwarded to first base station 103 or second base station 105 to the down link data that first subscriber equipment 101 sends from core net being used for of receiving being used to postpone non-sensitive service.
Specifically, can determine the switch transition time, and the down link data that received before this time is forwarded to first base station sending to first subscriber equipment, and any data that receive this time after are forwarded to second base station 105 with to 101 transmissions of first subscriber equipment.The switch transition time can be confirmed as the packet numbering, thereby switch controller 205 is transmitted the particular number of packet to first base station 103, and it continues to transmit data to second base station 105 then.
Therefore, data only are forwarded in the base station one in this operator scheme, and owing to eliminated the needs that duplicate and store of data communication, so can reduce the buffer requirements and the communication resource.Further, though owing to come from the re-transmission of first base station switching is delayed, because communication service is to postpone non-sensitive service, so this can be to perceptible quality generation great influence.
At the second operation switch mode that is being used for postponing sensitive service (for example service in real time), the down link data that sends to first subscriber equipment 101 that receives from core net be forwarded to first base station 103 and second base station 105 both.Therefore, during switching interval, both transmit packet to switch controller 205 to base station 103,105, thereby allow down link data to be sent by from the base station any and do not need the further participation of a RNC107.Especially, identical data can be stored in first and second base stations 103,105 in their transmission buffer.
Therefore, in this operator scheme, can use method more flexibly, send from only base station to allow data, and do not need at first data to be sent to another from a base station.Further, thus since packet is all available two base stations can be from only base station retransmitted data packet, so realized effective retransmission performance.
This method provides special superior function in the system that uses fast cell to select, wherein subscriber equipment 101 selects to receive from it base station of transmission.In second switch mode of operation, at the switching interval base stations during needed down link data is stored in the buffer, and therefore these data can be offered subscriber equipment 101 from selected base station, and do not need to come from any participation of a RNC107, need can being sent to first subscriber equipment 101 by air interface before, this not send any more multidata yet.
In specific example, second switch mode of operation is the shared data sending mode, wherein during switching interval packet by both are sent to first subscriber equipment from first and second base stations.
Therefore, realized short overlapping period (overlap period), source and target base station 103,105 all sends data to first subscriber equipment 101 in this period.Yet different with operating in soft handover, the identical traffic that comes from different base station in operating in soft handover is by in the first subscriber equipment 101 places combination,, the operation of system comprises that base station 103,105 carries out different transmissions to first subscriber equipment 101 among Fig. 1.Further, in the system of Fig. 1, be quadrature (in the resource allocation at quadrature), and first subscriber equipment 101 receive the transmission that is mutually independent in the transmission that comes from different base station during the switching interval.
Specifically, during overlapping period, Radio Resource is divided between first and second base stations 103,105.Temporal separation can be by distributing different transmission intercals (for example different time slots) to first and second base stations 103,105 and obtaining.Separation in the frequency domain can be by distributing different carrier frequencies to first and second base stations 103,105 and obtaining.
Typically, a certain amount of Radio Resource is assigned to communication service in cellular communication system.In example, the allocation of radio resources that is used for communication service during switching interval is divided between first and second base stations 103,105.In this example, do not need extra Radio Resource to support to share the transmission switch mode.
For example, in the embodiment of low complex degree, communication service is assigned with a time slot in each time frame, and the time slot of distributing to communication service can alternately be assigned to first base station 103 at the even number time frame, is assigned to second base station 105 at the odd number time frame.
In many examples, revising this division during switching interval is further advantage.Especially, division can be modified so that it changes to deflection second base station 105 from being partial to first base station 103 gradually.For example, independent time slot in the different time frame is assigned to first or second base station 103,105, be assigned to the time slot of first base station 103 and be assigned between the time slot of second base station 105 ratio can from switching interval begin basically change to end at switching interval basically less than one greater than one.This will allow with reflect mode to the most probable demand of resource with resource allocation to the base station.
In the system of Fig. 1, retransmission mechanism is used in the base station, does not wherein also have the correct packet that receives later being retransmitted from the base station.
In example, the re-transmission of packet is continued to support in base station 101, and wherein this packet was before sent by first base station 101 to share transmission mode during switching interval.Simultaneously, the previous new data packet that is not sent by first base station 103 is continued to send in second base station 103.
Therefore, in the system of Fig. 1, the switch mode of start-up operation, wherein source base station (i.e. first base station 103) continues to support the re-transmission of legacy data grouping, and target BS (i.e. second base station 105) is responsible for sending new data packet.
Cognoscible is that this division of responsibility does not need to be applied to whole switching interval, and just is activated after the given activationary time in switching interval.For example this activationary time can be determined by the signaling between the base station 103,105, for example uses first subscriber equipment 101 as control assembly.
Fig. 3 shows the example according to the direct-cut operation of the embodiment of the invention.The figure shows the example that is used to postpone sensitive switching of serving, and the example of second pattern of reflection switching, wherein during switching interval, use and share transmission mode.
In example, first base station 101 sends packet to first subscriber equipment 101 at first.In Fig. 3, the packet numbering is indicated by the numbering above the packet.Therefore first base station sends packet 60, heel packet 64 etc.Further, each packet is assigned a re-transmission identiflication number of indicating in packet.Therefore use and retransmit identiflication number 1 transmission packet 60.
In the example during packet 69 sends, at a time, first subscriber equipment 101 need to determine cell switch, and it sends cell switch message to first and second base stations 103,105.This cell switch message comprises the sign of the sub-district that direct-cut operation will take place, and promptly it comprises the sign of second base station 105.In addition, cell switch message comprises the indication to the data packet numbering, and second base station can begin to send from this packet numbering.In example, cell switch message indicates second base station 105 to begin to send packet from numbering 72.Because communication service is to postpone sensitive service, thus packet be switched controller 205 be downloaded to first base station 103 and second base station 105 the two.Therefore, second base station 105 can be after the first cell switch message be received the transmission of log-on data grouping soon.
In response to receiving cell switch message, first and second base stations 103,105 all enter the switch mode of operation at specific switching interval.During this switching interval, the available allocation resource that is used to serve is divided between first base station and second base station 103,105.By shown in the packet, this packet is before the duration during the switching interval doubles switching interval and the duration afterwards in Fig. 3 for this, and this indicates it to spend the time that sends to the given data amount that doubles.
During switching interval, the re-transmission to the packet of previous transmission is proceeded in first base station 103, because also successfully do not receive this packet (that is, NACK message or also do not receive feedback message) from first subscriber equipment 101.
Therefore, packet 61,62 in example, and 67 and 69 also are not successfully received.Therefore first base station 103 continues at first to send packet 61 during switching interval, is 62,67 and 69 then.Yet first base station 103 is not continued to send also not by first base station 103 and was sent once any new data packet.
Further, second base station 105 also enters switch mode and begins and sends packet to first subscriber equipment 101.Use sends these packets to the orthogonal resource allocation from the transmission of first base station 103, for example by using different time slots and/or different carrier frequencies.
Second base station 105 only use whole resources half begin to send.Therefore, as shown in Figure 3, the initial transmission of packet is used the length that doubles given data packet size.Second base station indicated packet numbering from cell switch message begins to send.Therefore, second base station 105 begins to send packet 72, then is packet 73, or the like.Thereby second base station 105 is further operated the retransmission mechanism of himself and is guaranteed that the packet that sends is successfully received by first subscriber equipment 101.
When switching interval finished, first subscriber equipment 101 or first base station, 103 signalings gave second base station 105 so that the indication to the packet of also not confirmed by first subscriber equipment 101 to be provided.Second base station 106 is continued the packet of retransmission of lost then.
In the example of Fig. 3, second base station 105 sends packet 62 and 67.Second base station 105 also sends any other packet that is not also sent by any base station, for example divides into groups 70 and 71.Further, when switching interval finished, the transmission to first subscriber equipment 101 is finished or finished in first base station.Therefore, second base station 105 is proceeded to be used for all Resources allocation of communication service to withdraw from switch mode and to be converted to normal running in normal running.Like this, after the switching interval, communication service is fully only supported by second base station.
Cognoscible is that the suitable data grouping can be determined in second base station in certain embodiments, starts transmission based on the re-transmission feedback message that is sent to first base station 103 from first subscriber equipment 101 from this suitable data grouping.For example, in Fig. 3, first subscriber equipment 101 had sent packet 69 soon before receiving cell switch message NACK message can be detected in second base station 105.By adding reflection packet numbering (it typically remains in the retransmission system), the suitable blank of packet, second base station 105 is determined the suitable data packet numbering then, for example packet 72, start from this packet numbering and transmit.
In certain embodiments, first subscriber equipment 101 can be set to whether supervisory work takes place to detect the switching mistake during switching interval.For example, first subscriber equipment 101 can detect first base station 103 and whether its transmission is not restricted to the packet that only retransmits previous transmission, or be limited on the resource time slot of being divided.Similarly, first subscriber equipment 101 can monitor whether second base station 105 does not begin to send packet, or whether it does not distribute these packets of transmission in the appropriate resources that is used for switching interval.Under these circumstances, first subscriber equipment 101 can be determined to switch mistake and taken place and can adopt remedial measures.
In the indication service is non-the delay under the sensitive situation of serving, and switch controller 205 will determine that it still is second base station 105 that each packet is forwarded to first base station 103.Specifically, for this switching can be determined the switch transition time, thereby be forwarded to first base station 103 in any packet that switch transition was received before the time, any packet that is received after the time in this switch transition is forwarded to second base station 105.Cognoscible is to indicate in any suitable manner the switch transition time, for example by clear and definite packet numbering, all is forwarded to second base station 105 from these all follow-up packets of packet numbering.
The switch transition time of switch controller 205 uses can be different change-over time with air interface in such embodiments, in this air interface change-over time, first subscriber equipment 101 is supported from being supported to change into by second base station 105 by first base station 103 by air interface.
For example, switch controller 205 is determined the switch transition times, this switch transition after the time all packets all be sent to second base station 105.Yet, finish re-transmission in order to allow first base station 103 to the packet of sending (and not being forwarded to second base station 105) from first base station 103, first subscriber equipment 101 continues to be supported by first base station 103 in a specified time interval.When this finishes at interval, any remaining unacknowledged data grouping will be forwarded to second base station 105 to send to first subscriber equipment 101.
The switch transition time really usual practice as depending on the signaling that comes from first subscriber equipment 101.Especially, first subscriber equipment 101 can send and comprise the cell switch message of indicating last received packet, it can be forwarded to the switch controller 205 of being responsible for determining the suitable data grouping, wherein forward the data to second base station 105 from this suitable data grouping.
Specifically, switch controller 205 all packets of continuing to be received after receiving cell switch message are forwarded to second base station 105 rather than first base station 101.
Cognoscible is that for the sake of clarity foregoing description has been described embodiments of the invention with reference to different functional unit and processor.Yet cognoscible is to use any suitable function between different function units and processor to distribute, and the present invention that can not detract.For example, be described to carry out by identical processor or controller by the function of independent processor or controller execution.Therefore, the reference of special function unit only is counted as reference to suitable equipment, so that described function to be provided, rather than strict logic OR physical structure or the tissue of expression.
The present invention can realize with any suitable form, comprise hardware, software, firmware or any their combination.Selectively the present invention realizes as the computer software that moves on one or more data processors and/or digital signal processor at least in part.The assembly of the embodiment of the invention and parts can in any suitable manner and physically, functionally and logically be realized.In fact, function can be in single unit, in a plurality of unit or as the part of other functional units and realize.Like this, the present invention can realize in single unit or physically and functionally be distributed between different units and the processor.
Described the present invention though got in touch some embodiment, its particular form that is not proposed here limits.On the contrary, scope of the present invention is only limited by appended claim.In addition, though contact specific embodiment and described feature, those skilled in the art understand that a plurality of features of described embodiment can be according to the present invention and combination.In the claims, term " comprises " appearance of not getting rid of other assemblies or step.
Further, though listed independently, a plurality of equipment, assembly or method step can be realized by for example single unit or processor.In addition, though independent feature may be included in the different claims, they may advantageously be combined, and are included in the different claims and do not mean that the combination of feature is not feasible and/or favourable.Equally, feature is included in the restriction that does not mean that in the class claim such claim, but indicates this feature to be equally applicable to other suitable claim classifications.Further, the order of feature does not mean that feature must be with this any particular order of moving in the claim, especially, in the claim to a method separately the order of step do not mean that step must carry out in proper order with this.On the contrary, step can be carried out with any suitable order.